What you see: Guacamole that’s brown and yucky on top.
What it is: Guac that turned brown because it was exposed to air.
Eat or toss? Toss the brown layer, but excavate under it until you get to green. As long as your guacamole is relatively fresh, any green areas should still be fine to eat.
So, can you eat guacamole that’s turned brown?
This guacamole may look like a mucky swamp, but buried beneath that layer of yuck, there’s hope for your tortilla chips.
The guac turned brown simply because it was exposed to air. An enzyme in the avocado reacted with oxygen and that sad brown color was the result. The same thing happens to apples and other fruits and vegetables and even shrimp when they’re injured or their inner flesh is exposed to air (scientists call this “enzymatic browning” and it involves various types melanin). So, nothing to fear here, but the oxidized avocado may not taste so great.
If you scrape off the brown part, you’ll get to a subterranean layer of perfectly good guacamole. That’s because the top layer of guac guarded the layer below from the oxygen in the air.
How to avoid brown guac
So, brown guacamole is still salvageable, but there are also loads of ways to prevent this problem in the first place. The key is just to block air from coming into contact with the avocado-y goodness. You can do this by squirting lemon or lime juice all over the surface of the guacamole, which will make conditions too acidic for the browning reaction to take place. That’s my favorite method.
Here’s my take on other approaches to prevent oxidation from ruining your guacamole (spoiler (ha!) alert: I think these all have drawbacks and the lemon juice method really is the best!):
- ‘Leave the avocado pit in the guac.’ This old wives tale does not work. It will, however, preserve green guacamole just under the seed, as it will block oxygen exposure in only that spot.
- ‘Apply a sheet of plastic wrap to the top of the guacamole.’ Eh. This will provide a barrier, but why contribute to plastic waste? When you lift up the sheet the next day, inevitably some guac will come along too, which isn’t ideal.
- ‘Pour a thin layer of water onto the surface, then pour the water off when you’re ready to dip your tortilla chips.’ The Today Show evaluated a number of tactics and they liked the water trick the best. I’m not a fan of the water method as I find it soaks into the guac a little bit and dilutes the texture and flavor.
Thanks to Joe G. for submitting these photos. Joe reports that he successfully scraped off the brown layer. For science, he sampled the brown area and found it to be “yucky.”
“Not overpowering, but it had sort of a stale taste,” he wrote. “Wasn’t pleasant.”
But, he kept digging and reported: “The green beneath the brown tasted perfect.”
Are you in pre-guac mode, sizing up a brown avocado? Avocados can have discoloration for a number of reasons, including injuries, too-cold storage and being squeezed too hard by supermarket shoppers. Check out the EatOrToss Avocado Index for more help decoding their mysterious ways.
- Frequently Asked Avocado Questions – AvocadoCentral.com
- The best way to keep guacamole green, revealed – Today Show Apple slices turned brown: Are they really bad apple or just misunderstood? – EatOrToss.com
- The Chemistry of An Avocado – Compound Interest
What’s up, Guac?
This post was first published on Nov. 6, 2017, and updated on Jan. 18, 2023.